1. Introduction
This invention relates to hot melt adhesives and more particularly, to hot melt adhesive formulations in combination with a fuel capable of undergoing sustained burning when ignited.
2. Description of the Prior Art
The term "hot melt" is quite well known in the art and refers to bonding agents which achieve a solid state and resulting strength by cooling, as contrasted with other adhesives which achieve the solid state through evaporation, by removal of solvents, or by cross-linking. When cold, hot melt adhesives are thermoplastic solid materials. Application of heat brings the hot melt adhesives to a liquid, tacky state and after removal of the heat, the adhesive sets by simple cooling. Hot melt adhesives provide almost instantaneous bonding together with a high degree of wetting. Typical early hot melt adhesives are based upon rosin and its derivatives; alkyds; terpene resins and heat-stable phenol-formaldehyde resins and the like. Current hot melt adhesives are based upon various polyamines and polyamides. All of the foregoing are frequently modified with higher molecular weight polymers such as ethyl-cellulose, polyvinylacetate and its derivatives, butylmethyl-acrylates, polyethylene, polystryene and styrene copolymers and polyisobutylene. Commercial examples of such hot melt adhesive formulations include olefin polymer or copolymer-based adhesives sold by Borden Chemical Company under the trade designation MA-5423, MA-5428 and HM-109-34; modified polyethylene based adhesives sold by the Eastman Chemical Company under the trade designations Epeline C-17, Eastobond L-808/91 and Eastobond L-8080/38 and by the H. B. Fuller Company under the trade designation HM 131-R, HM 212 R and HM 065 R; and by the General Mills Corporation under the trade designation Versalon 1010, 1055 and the like. Hot melt formulations are disclosed in U.S. Pat. Nos. 2,153,660; 2,886,543; 3,242,141; 3,377,303; and 3,400,038; all incorporated herein by reference.
Hot melt adhesives are typically used in the melt by heating the adhesive in a vessel and applying the same by brushing the adhesive onto the workpiece. It is recognized in the art that this is not a fully satisfactory method for applying a hot melt adhesive, especially with small scale applications such as for home use, since it involves the use of a pot or other vessel for heating the adhesive which is difficult to clean and a soft brush for each application. As a result, an improved means for applying hot melt adhesives have been developed whereby an applicator gun is filled with the adhesive in solid form. The application gun has heating means and a nozzle so that the adhesive is heated to a viscous liquid form and squeezed out of the nozzle in the desired form of a smooth, liquid bead. Such an applicator gun is expensive for home use and requires frequent cleaning to unclog its nozzle. Moreover, upon application of a bead of the adhesive, the bead cools rapidly loosing its tacky state. Thus, to adhere an assembly of parts, there is little time to place the parts together and it is difficult to reposition the parts once assembled.